My wordpress site doesn't render correctly on larger monitors

I've been working on this site for the last couple of days. Everything was going perfectly well on my 13" laptop - and even on the 17" PC laptop I checked it on. However, the magazine owners looked at it on a 21" screen earlier today and apparently it looks radically different. I j开发者_JAVA技巧ust checked it on a monitor in an Internet cafe, and it appears they have a point. Can anyone help?

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In the style sheet, replace

body { color:#000; background:url(images/bg.jpg) fixed; }

with

body { color:#000; background:url(images/bg.jpg) fixed no-repeat center; }

Then, center the content with

body {width: 600px; /* from the background image */ margin: 0 auto; }

this should work better.